Spark plug cleaning and setting tool



Dec. 25, 1934. w. H T AA 1,985,410

SPARK PLUG CLEANING AND SETTING TOOL Filed Dec. 1Q, 1932 INVENTOR A fjmm Patented Dec. 25, 1934 UNITED STATES PATENT OFFICE Eng Application December 10, 1932, Serial No. 646,626 In Great Britain August 30, 1932 10 Claims.

This invention relates to a tool for the cleaning and setting of the electrodes of spark plugs.

Hitherto the cleaning and setting of spark plug electrodes has been a tedious process which normally comprises the manual scraping or brushing of the said electrodes and plug walls by means of scraping or brushing elements. A principal object of the invention is to provide a tool which can be used for cleaning electrodes of spark plugs and which can also be utilized for setting said electrodes, the said tool being adapted for use either as a cleaning tool or as a setting tool, or as a combined cleaning and setting tool. The tool constructed in accordance with the invention comprises a gauge element for the spark gap and means to force the electrodes to contact with the gauge. During relative movement between said members and the electrodes, the latter are cleaned, which may be effected by forming the gauge and/or pressing element of material adapted to exert a scraping or abrasive action on the electrodes.

The invention will be hereinafter more particularly described with reference to the accompanying drawing, in which:-

Fig. 1 shows a view in perspective of one side of the device.

Fig. 2 shows a view in perspective of the other side of the device.

Fig. 3 shows the device applied to a spark plug having an axially directed gap.

Fig. 4 shows the device applied to a spark plug having a radial gap.

Fig. 5 shows details of modifications. Fig. 6 shows in perspective a somewhat modified embodiment. 7

Referring to Figs. 1-4 of the drawing, the device comprises an outer shell like member 10 which is internally recessed and is provided with a thread 11 on its inner walls adapted to engage with the thread of the spark plug by which the same is normally mounted in the cylinder head. If desired, the outer surface of the shell 10 may be provided with knurling or the like 12 to facilitate manipulation of the same.

Arranged within the internal recess 13 of the shell 10 is a tubular gauge member 14. This tubular member may be formed in any desired manner but in the illustrated embodiment is shown as a bent strip of steel plate of a thickness corresponding to the correct gap between the earthed and central electrodes of the spark plug. The tubular member 14 projects somewhat beyond the edge of the recess 13 as shown more clearly in Fig. 4 and may be provided with scraping or brushing elements 15 adapted for various cleaning operations and more particularly described later.

Arranged concentrically with the tubular member 14 is a further slotted cylindrical member 16 having a conical outer face 17. The diameter of the member 16 is so chosenas to be somewhat less than the outer boundaries of the radially projecting tine or tines forming the earthed electrodes of the plug.

The member 16 may be secured in position within the shell 10 by means of a screw or the like member 18 while the tubular element is shown as being pressed into a recess in the centre part of the member 16. If desired, however, the members 14 and 16 may be mounted within the shell 10 so as to be otherwise readily removable so that the same shell is adapted to receive different members 14 and 16 according to variations in the spark gap of the plug it is desired to clean and set.

Further, the outer edge of the tubular member 14 may, if desired, be bevelled or chamfered as indicated at 45 in Fig. 6 so as to facilitate its introduction into the radially disposed spark gap as hereinafter described. It is of course understood that the internal diameter of the tubular member 14 should correspond substantially to the external diameter of the central electrode of a spark plug.

Arranged at the end of the shell 10 remote from the recess 13 is a transverse member 19 which may conveniently form key means for turning the shell 10 when applied to a spark plug for cleaning and setting the same. The key 19 carries two spaced arms 20, 21 which are mounted on a pivot 22. The outer ends of the arms 20, 21 are maintained spaced by a pin 23. The outer end of one of the arms, for example the arm 20 is formed of suflicient thickness to comprise a gauge adapted for the spark gap of a spark plug having an axially disposed gap. This outer end of the arm 20 may be scored or otherwise roughened as shown at 27 to provide an abrasive actiofi. The other arm 21 opposite the gauge portion of the arm 20 carries a threaded spindle 24 operated by means of a milled head 25 and carrying on its inner end a fiat disc or the like 26 having its outer face scored or otherwise roughened to form an abrasive surface as shown at 28. v

To allow the arms 20, 21 to lie against the lateral faces of the key member 19 the latter is preferably slotted as shown at 29 and 30 to receive the members arranged between the arms 20, 21.

The application of the tool to the cleaning and setting of spark plug electrodes having axially directed spark gaps is shown more particularly in Fig. 3. The arms 20, 21 are swung to a position substantially at right angles to the member 19 and the outer end of the arm 20 forming the gauge is introduced into the spark gap in a direction transverse to the axis. The disc 26 is then operated by means of the milled head to press the grounded or earthed electrode 31 down towards the central electrode 32 and the electrodes are cleaned by any suitable movement of the members 26, 2'7 relatively thereto. For example, the abrasive or like surfaces 27, 28 may be reciprocated substantially radially or the device may be rotated about the axis of the central electrode 32. When the electrodes have been sufficiently cleaned the member 25 is screwed down until the gauge end of the arm 20 is clamped tightly between the electrodes 31, 32, thus ensuring the correct setting of the same and then the disc 26 is unscrewed and the tool removed from the plug.

In the application of the device to a spark plug 41 (Fig. 4) having radially directed spark gaps,

the tubular member 14 is introduced into the radial gap for the central electrode 33. The tubular member 14 preferably projects beyond the outer face of the shell 10 to such an extent as to allow the scraper or like member mounted thereon to be clear of the underside of the radially projecting tines 34 forming the earthed electrodes when the thread 11 engages the thread 35 of the plug 41. The application of the tubular member 14 to the central electrode 33 provides a scraping action on the latter and when the threads 11, 35 engage, the tubular member 14 is rotated around the central electrode and scrapes or rubs the same clean. After screwing the shell 10 down on the plug some distance the conical face 17 of the member 16 contacts with the radial electrodes 34 and presses the same downwardly and inwardly until the points of the electrodes contact with the outer surface of the tubular member 14. During this action the outer faces of the electrodes 34 are cleanedby the rubbing action of the conical surfaces 17 and the electrodes 34 are set to the correct gap by the pressure of the conical surfaces 17. When the correct setting has been obtained no further screwing down of the shell 10 is possible and the same is then unscrewed from the plug 41, during which unscrewing cleaning of the radially inner points of the electrodes 34 will be effected.

The member 15 is, as shown in Fig. 4, adapted to contact with the inner wall of the plug 41 and cleans the same by means of a. scraping action. The member 15 however, may be modified in many different ways. For example, as shown in Fig. 5, the tubular element 14a may be provided with spring arms 36 which, onapplication of the shell 10a to the plug, contact with the conical mica or other insulator 3'7 of the central electrode and exert a scraping action on the same. The spring arms 36 are preferably so constructed as to be forced from the position shown in dotted lines into the position shown in full lines in Fig. 5 so that they may exert a gradually increasing scraping action on the conical insulation 37. In addition to the scraper arms 36 the tubular element may be provided with a set of wire bristles 38 adapted to contact with and clean the inner wall of the plug. The setting and cleaning member 16for the earthed electrodes as shown in Fig. 4, is held in position by a screw 18. If desired, however, as shown in Fig. 5, the member 16a may be arranged so as to be freely rotatable within the shell 10a, for example by locating the same in a recess 42 in the shell and turning the edge 43 of the recess 42 over a flange 44 provided on the member 16a.

The tubular member 14 is described and illustrated as comprising a bent steel strip, in which case it is preferred to provide a longitudinally extending slot 39 (Fig. 2).

The embodiment shown in Fig. 6 corresponds substantially to the view shown in Fig. 2 with the addition that the pressing surface 17b is formed as an abrasive surface while both the inside and the outside surfaces of the tubular member 14b are also formed as abrasive surfaces. As indicated at 45 the outer end of the tubular member is bevelled or chamfered while the slot 39b in the tubular member 14b is also bevelled or chamfered as shown at 46.

In some cases it may happen that the earthed electrodes 34, Fig. 4, when in their fouled condition are too close to the central electrode 33, although it is more usual for the gap between the electrodes to be increased beyond the correct dimension by virtue of the burning away of the earthed electrodes. Where, however, the gap is smaller than that required, the insertion of the bevelled end of the tubular scraping and gauge member 14b forces the earthed electrodes away from the central electrode. Where the gap is too small to allow the insertion of the outer end of the member 14b then the earthed electrode must primarily be bent away from the central electrode by another tool to increase the gap.

The hitherto usual manner of setting the electrodes by means of a, gauge member has been 3 to hold the gauge member against the central electrode and to tap the earthed electrodes, for example by means of a hammer or punch, or otherwise bend the same over, until they contact with the gauge. Owing, however, to the fact that the metal of the earthed electrodes is somewhat resilient they spring back slightly after being set against the gauge, so that further adjustment has been necessary after the gauge has been removed. It has, however, been found that on the application of the tool of the present invention the gradually increased pressure of the pressing element which causes the bending of the earthed electrodes and set up by the threaded connection of the pressing element is such that there is no or at the most only a very minute spring-back of the earthed electrodes from their set position. In any case even when there is some slight springback after adjustment to gauge distance, this spring-back is well within the allowable upper limit for the correct gauge distance.

It is to be understood that the term abrasive or abrasive surface used throughout this specification and claims means a surface which is so inherently rough as to provide an abrasive action or a surface which is scored or otherwise roughened so as to provide an abrasive or scraping action.

What I claim is:-

1. A tool for cleaning and setting closer together the electrodes of spark plugs having a free spark gap and a central electrode and at least one earthed electrode which includes a gauge element for the spark gap adapted to contact with said central electrode, the portion of said element which contacts said central electrode having an abrasive surface, and means to press said earthed electrode into contact with said gauge element when the latter is inserted in said gap and contacting said central electrode.

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with said central electrode, the portion of saidelement which contacts said central electrode having an abrasive surface, and screw operated means to press said earthed electrode into contact with said gauge element when the latter is inserted in said gap and contacts said central electrode.

3. A tool for cleaning and setting closer together the electrodes of spark plugs having a central electrode and at least one earthed electrode spaced to form a radially directed spark gap including a tubular gauge element constructed to fit around and contact said central electrode within said gap and formed to exert an abrasive action on said central electrode, and means to press said earthed electrode into contact with said tubular gauge element.

4. A tool for cleaning and setting closer together the electrodes of spark plugs having a central electrode and at least one earthed electrode spaced to form a radially directed spark gap which includes a tubular gauge element formed to fit around and contact said central electrode within said gap, abrasive surfaces on the inner and outer faces of said tubular element, and means to press said earthed electrode into contact with said tubular gauge element.

5. A tool for cleaning and setting closer together the electrodes of spark plugs having an insulated central electrode and at least one earthed electrode spaced to form a radially directed spark gap which includes a tubular gauge element formed to fit around and contact said central electrode within said gap, the inner face of said element being an abrasive surface, means connected with said tubular element and formed to contact with the surfaces of the insulation of said central electrode, and means to press said earthed electrode into contact with said tubular gauge element. 1

6. A tool for cleaning and setting closer together the electrodes of spark plugs having an insulated central electrode and at least one earthed electrode spaced to form a radially directed spark gap including a tubular gauge element formed to fit around and contact said central electrode within said gap, abrasive surfaces on the inner and outer faces of said element, and a conical surface located adjacent one end of said tubular element and adapted on axial movement of said tubular element to press said earthed electrode into contact with said tubular gauge element.

7. A tool for cleaning and setting closer together the electrodes of spark plugs having an insulated central electrode and at least one earthed electrode spaced to form a radially directed spark gap including a tubular gauge element formed to fit around and contact said central electrode within said gap, abrasive surfaces on the inner and outer faces ofsaid tubular element, and a conical abrasive surface located adlacent one end of said tubular element and adapted on axial movement of said element to press said earthed electrode into contact with said tubular gauge element.

8. A tool for cleaning and setting closer together the electrodes of spark plugs provided with an insulated central electrode and at least one earthed electrode spaced to form a radially directed spark gap and with a threaded casing comprising, in combination, a cylindrical cap-like shell, a tubular gauge adapted to fit around and contact said central electrode within said gap mounted coaxially within said shell, abrasive surfaces on the inner and outer faces of said element, means mounted in said shell concentrically with and axially displaced from the outer end of said tubular element and adapted on axial movement of said shell to press said earthed electrode into contact with said tubular gauge element, and screw threads formed on the cylindrical wall of said shell adapted to engagewith the threaded casing of said plug.

9. A tool for cleaning and setting closer together the electrodes of spark plugs provided with an insulated central electrode and at least one earthed electrode spaced to form a radial spark gap and with a threaded casing, comprising, in combination, a cylindrical cap-like shell, a tubular gauge element adapted to fit around and contact said central electrode within said gap mounted coaxially within said shell. abrasive surfaces on the inner and outer faces of said element, means mounted in said shell concentrically with and axially displaced from the outer end of said tubular element and adapted on axial movement of said shell to press said earthed electrode into contact with said tubular gauge element, means connected with said tubular element and formed to contact with the surface of the insulation of said central electrode, means connected with said tubular element and formed to contact with the inner wall of said plug casing, and screw threads formed on the cylindrical wall of said shell adapted to engage with the threaded casing of said plug.

10. A tool for setting closer together the electrodes of spark plugs provided with an insulated central electrode and at least one earthed electrode spaced to form a radial spark gap and with a threaded casing, comprising, in combination, a cylindrical cap-like shell, a tubular gauge element adapted to fit around and contact said central electrode within said gap mounted coaxially within said shell, means mounted in said shell concentrically with and axially displaced from the outer end of said tubular element and adapted on axial movement of said shell to press said 

